The effectiveness of breeding boars in insemination depends mainly on the skill of optimal use of their reproductive potential. Nevertheless, their semen is highly variable in its quality and physical characteristics, which makes it difficult to organise semen production for artificial insemination purposes. The present study contains an analysis of semen collected from Polish Landrace breed boars -the most popular pigs bred in Poland. It demonstrates that there is a statistically significant interaction between season of birth and reproductive season of Polish Landrace boars. What is more, it proves that these significant differences between reproductive performances of boars are closely connected to their breeding season and seasons of their birth and life. The results also illustrate how to improve organisation of insemination centres and make them better financially efficient. STRESZCZENIEEfektywność użytkowania rozpłodowego knurów zależy od umiejętności optymalnego wykorzystania ich potencjału rozrodczego. Jednak nasienie pobierane od knurów inseminacyjnych wykazuje dużą zmienność w zakresie parametrów fizycznych i jakościowych, co utrudnia właściwą organizację produkcji nasienia przeznaczonego do inseminacji. W przeprowadzonych badaniach wykazano statystycznie istotne współdziałanie sezonu urodzenia i sezonu użytkowania rozpłodowego w kształtowaniu wszystkich parametrów fizycznych nasienia knurów rasy polskiej białej zwisłouchej. Stwierdzone w badaniach istotne różnice między wynikami użytkowania rozpłodowego związane z sezonem urodzenia i eksploatacji rozpłodowej knura wskazują na konieczność uwzględnienia tych czynników w procesie selekcji. Uzyskane wyniki wskazują, że może to przynieść wymierne korzyści organizacyjnoekonomiczne przyczyniające się do poprawy funkcjonowania stacji unasieniania loch.Słowa kluczowe: sezon urodzenia, sezon pobierania nasienia, nasienie, rasa, cechy ejakulatów 272

The study aimed to investigate changes in semen parameters of insemination boars of selected breeds with reference to seasonal changes in the properties of ejaculates in the European boar (Sus scrofa L.). The material for the study covered 88000 ejaculates obtained from boars of the following breeds: Polish Large White, Polish Landrace, Duroc, Hampshire, Pietrain, Duroc×Pietrain, Pietrain×Duroc. The results of the research indicate that seasonal changes in the quality of the produced ejaculates, similar to those occurring in the males of the wild boar, still occur in insemination boars. The observed changes concern above all the volume of the ejaculates, the total number and concentration of spermatozoa. Seasonal variation in the quality of the produced ejaculates is fixed and has not decreased in the recent years despite the conducted breeding activities, selection and the limitation of the influence of environmental factors.

No abstract

Artificial insemination constitutes the main method of pig breeding in Europe. According to literature, statistical models which allow prediction of productive capacity can be used as additional tools which may be helpful in making selection decisions concerning breeding boars. The aim of the research was to evaluate the influence of boar's age, standardized daily growth rate, standardized meat content in the carcass, the number of nipples, the age when the boar starts to be used for breeding, the number of semen collections per month, and the interval between semen collections on selected qualitative and quantitative parameters of the semen and to calculate multiple regression equations, which would allow prediction of productive capacity of AI landrace boars. The material for the analysis comprised 47596 ejaculates obtained over the period 1995-2014 from 306 Polish Landrace boars. The obtained results show that semen parameters of the examined boars depend on physiological and organizational factors included in the analysis. It was observed that the following factors, measured with the number of produced semen doses, were of particular significance for the efficiency of use of the boars: boar's age, the daily growth rate, meat content in the carcass, as well as the number of collections and the interval between collections. The conducted statistical analysis points to the possibility of predicting semen parameters accurately using regression analysis. The models are characterized by very high accuracy, which points to their potential for application. The calculated determination coefficients for the multiple regression equations assumed the R 2 value of above 0.92. The highest value of the determination coefficient (R 2-0.99) was obtained for the percentage of sperm cells showing progressive motility. The calculated regression equations may be used in the management of the stock of breeding boars and when making selection decisions.